In the fields of medicine and general research it is often necessary to provide injections of medicinal fluids or take fluid samples from a mammalian patient or subject and in particular a human. Injection may be by way of an IV needle, hypodermic injection and the like. For placement of injection needles of any kind, complications may arise when the subject of the injection is a vein.
Veins may be distinguished from arteries in that veins carry blood which has been spent of oxygen and return spent blood to the heart. Veins may typically have less pressure than arteries and are often more problematic for injection purposes.
Since veins carry exhausted blood at a lower pressure, veins do not "stand out" as readily for injection purposes as do arteries and accordingly do not provide as stable a surface to push against during the initial insertion of a needle or other injection means. Veins may move position, may be different in position from one subject to another, and may collapse if traumatized severely enough by repeated injection attempts. Because of movement, veins may be missed altogether. Improper insertion pressure due to sudden vein movement or uncertain placement may cause a needle or other means to penetrate both sides of the vein.
Because of the risk of discomfort to the patient and possible damage to veinous and surrounding tissues, trained technicians are often used to administer injections and IVs. While a significant amount of skill is necessary, devices which assist the process of injection are often used. These devices range in type and complexity but are accompanied by disadvantages.
Harvey (U.S. Pat. No. 5,254,095) discloses a vein tenter which may be used to pinch a portion of skin under which a vein may be positioned. Harvey's device may be positioned at various angles relative to a subject vein in order to facilitate puncturing the vein. Harvey's device however requires constant pinching pressure by the user in order to maintain a hold upon the device. If a user momentarily releases pressure on the device, the device may lose its position on the subject vein possibly causing damage or slippage of the injection device.
Gubich (U.S. Pat. No. 5,147,306) discloses a device for puckering flesh in order to facilitate injections. Gubich's device facilitates self-injection using spring biased jaws forming a clamp, which can be opened by applying pressure to jaw ends with a thumb and forefinger, displacing the device upon a subject vein and closed by relieving pressure between the thumb and forefinger. Gubich's device however, does not account for veins of different sizes and may apply different pressures depending on the size and location of the vein to be punctured. Constant pinching pressure from the Gubich device may also cause discomfort on some patients and may cut off blood flow in the subject vein on others.
Other devices are available which provide varying degrees of success for stabilizing veins for puncture, yet all having disadvantages. While some devices consist of complicated straps and guides, others may be simpler yet fail to accommodate veins of different sizes. It would be desirable therefore to have a device that is capable of stabilizing veins for puncture, easy to use, simple in construction, and yet capable of accommodating veins of different sizes with a consistent level of comfort to the patient or subject.